1. Field of the Invention
The present invention is in the field of watermattresses. More particularly, the present invention is in the field of tube-type watermattresses having an immovable wave-dampening insert.
2. Brief Description of the Prior Art
Watermattresses have been known in the prior art for a long time. To a great many people sleeping on a watermattress offers more comfort than sleeping on conventional bedding. Nevertheless a serious disadvantage of conventional watermattresses is the wave motion of water in the mattress which, although preferred by some, is found objectionable by the majority of persons. In order to reduce or eliminate this unwanted wave motion various devices and means have been employed in the prior art. For example, U.S. Pat. No. 4,301,560 describes the use of lofted polyester fiber as a wave dampening insert in a watermattress. U.S. Pat. No. 4,411,033 describes the use of buoyant floating polyurethane foam insert as wave-dampener in a watermattress. U.S. Pat. Nos. 4,577,356, 4,551,873, 4,399,575, 4,345,348, and 4,247,962 describe the use of wave dampening baffles in watermattresses.
U.S. Pat. No. No. 4,221,013 describes the use of elongated water-filled tubes in a watermattress having a soft-sided (foam) frame of specific construction. When the water-filled tubes are disposed "head-to-toe" in the watermattress, they substantially prevent propagation of wave motion in a side-to-side direction. Inserts, (such as foam or fiber) have also been used in the prior art within the elongated tubes to dampen the propagation of wave motion in the longitudinal direction. A tube-type watermattress which has inserts capable of inhibiting wave motion and providing extra support to the back, "lumbar" area to a person resting on the watermattress is described in our U.S. Pat. No. 5,077,848.
Providing wave dampening inserts and/or baffles in a watermattress, however, is not entirely without problems. For example, baffles welded directly to the vinyl envelope which contains the water usually weaken the overall construction and eventually cause tears and leaks. Inserts, such as foam or fiber, cause their own sets of problems, such as difficulty in draining, and shifting within the water-tight envelope. In order to reduce these problems, techniques were developed in the art to facilitate draining and to anchor or tether baffles and inserts within the interior of the watermattress. Anchoring or tethering structures are described in U.S. Pat. Nos. 5,152,020, and 5,062,170. U.S. Pat. No. No. 5,050,257 describes a fiber-filled watermattress with a drainage manifold positioned beneath the fiber insert to direct water toward a drain valve, to facilitate draining of the watermattress.
With respect to tube-type watermattresses however, the problem of a fiber or foam insert sliding within the tubes, and bunching up ("balling up") within the tube, has not been solved until the present invention. This is so, because, until the present invention, the wave-dampening foam or fiber insert provided in a tube-type watermattress has been allowed to move freely within the mattress. Because users often fill the individual water-containing tubes of a tube-type watermattress at a faucet and then carry the filled tube to the bed (sometimes in a folded U-shaped configuration) or otherwise tend to lift and move the water-containing tubes of such a watermattress, the bunching up or "balling up" of inserts in the tubes is a serious problem in the art. Such bunching up of the insert can also occur over a course of time as a result of normal human activities on the watermattress. The present invention serves to eliminate this problem.